Age-hardenable nickel alloy



July 24, 1962 H. EISELSTEIN AGE-HARDENABLE NICKEL ALLOY Filed Nov. 13, 1958 S. E E E .I.

. F m m I W W LF L F E EV. R0 Du Du T T U0 U U 00 O 00 M M H2 H H 4 O O 0 0 O 00 R R m m m A B E O O O O O O 6 2 8 4 O 2 61 009 IQZMEZ NICKEL CONTENT% HERBERT LOUIS EISELSTEI N INVENTOR.

ATTORNEY 5,040,108 Patented July 24, 1962 ice 3,046,103 AGE-HARBENABLE Nl-QKEL ALLQY Herbert L. Eiselstein, Huntington, W. Va, assignor to The International Nickel Company, inn, New York, N.Y., a corporation of Delaware Filed Nov. 13, 11958, Ser. No. 773,702 9 Claims. (Cl. 75-171) The present invention relates to a malleable and agehardenable nickel-chromium base alloy and, more particularly, to a malleable nickel-chromium base alloy having a particularly high combination of strength properties and ductility over the temperature range extending from room temperature to approximately 1400 F.

It is well known that there are a number of age-hardenable nickel-base alloys available to the art for service at ordinary room temperature and at elevated temperatures. These prior art alloys have been characterized by disadvantages either from the standpoint of strength or from the standpoint of ductility. Thus, While many such alloys are capable of developing high tensile strength in the agehardened condition, they are characterized by an unsatisfactorily low yield strength as conventionally measured by the stress required to produce a set of 0.02% or 0.2% upon a specimen of the alloy in the tensile test. Conversely, many prior art nickel-base, age-hardenable alloys having satisfactory strength propertie Were characterized by an unsatisfactorily low ductility. In addition, many of the prior art age-hardenable nickel-base alloys displayed a brittle range at temperatures on the order of 1200 F. Designers of equipment for service at high stress and elevated temperature have required that a nickel-base alloy possess a yield strength representing a high proportion of the tensile strength thereof since the yield strength is the property of the alloy employed by the designer, In addition, age-hardenable nickel-base alloys having improved ductility in combination with improved strength properties were required by the art. Although attempts have been made to overcome the foregoing difficulties, none, as far as I am aware, Was entirely successful when carried into practice commercially on an industrial scale.

It has now been discovered that a special age-hardenable, malleable, nickel-chromium base alloy containing special controlled and coordinated amounts of alloying elements possesses an improved and outstanding combination of high strength and high ductility over a wide temperature range extending from ordinary room temperature up to about 1400 F.

It is an object of the present invention to provide a malleable, age-hardenable, nickel-chromium base alloy having an improved combination of high strength and high ductility over a Wide range of temperatures.

Another object of the invention is to provide an improved nickel-chromium base alloy of specially controlled composition which exhibits a high rupture life at elevated temperatures.

The invention also contemplates providing an improved age-hardenable nickel-chromium base alloy having a yield strength representing a very high proportion of the tensile strength in the age-hardened condition while at the same time displaying a very high elongation.

Another object of the invention is to provide an improved age-hardenable nickeLchromium base alloy which is readily producible in usual mill forms such as sheet, rod, tubing, shapes, etc.

Other objects and advantages of the invention will become apparent from the following description and from the drawing which depicts strength properties for alloys contemplated in accordance With the invention over a range of nickel contents and over a range of temperatures.

The present invention particularly contemplates a nickel-base alloy containing about 4.0% to about 8.0% columbium, about 2% to 4% molybdenum, about 15% to about 23% chromium, about 0.2% to about 2% aluminum, about 0.2% to about 2% titanium, not more than 0.5 silicon, with the sum of the aluminum and titanium contents not exceeding about 2%, up to about 0.1% carbon, up to about 0.5% zirconium, about 0.005% to about 0.015% boron, up to about 1% manganese, up to about 30% iron, and the balance essentially metal from the group consisting of nickel and cobalt, said balance being about 45% to about 58% or 60% of the alloy with the cobalt content being up to about 30% and with the nickel content being at least 30% of the alloy. These alloys are characterized by a very high combination of tensile strength and ductility as measured in the room temperature tensile test and will provide a yield strength (0.2% set) in the annealed and age-hardened condition of at least about 100,000 p.s.i. coupled with a high elongation which will usually be at least about 20%. In addition, these alloys will provide very high rupture strength in the age-hardened condition at temperatures on the order of about l200 F. to about 1350 F. or 1400 F. For example, the age'hardened alloys will usually provide a rupture life of at least about hours under a stress of 90,000 psi. at 1200 F. along With an elongation of at least about 5% and with a fracture frequently of the cupand-cone type. Within the foregoing compositional ranges, maximum tensile properties occur in the range of about 45% to 58% nickel, while maximum rupture properties at 1200 F. occur in the range of about 51% to about 56% nickel plus cobalt With the nickel being at least 30%. A preferred alloy contemplated in accordance with the invention contains about 0.03% carbon, about 0.18% manganese, about 0.27% silicon, about 53% nickel, about 21% chromium, about 0.6% aluminum, about 0.6% titanium, about 4% columbium, about 3% molybdenum, about 0.009% boron and the balance essentially iron. The sum of the columbium and molybdenum contents preferably is at least about 7%. Aluminum and titanium in small amounts impart malleability, age hardenability and high strength to the alloy and must be present in amounts of at least about 0.2% each. Molybdenum in the alloy contributes to the strength properties thereof at elevated temperatures but does not contribute age hardenability to the alloy. The molybdenum content of the alloy may be replaced by an equal weight amount of tungsten while retaining substantially the same properties although the hot malleabillty of the alloy is reduced thereby. columbium in the alloy may be replaced in part with tantalum in the amount of up to 4% of the alloy without materially changing the properties of the alloy. In partially replacing the columbium content of the alloy with tantalum, double the weight of tantalum should be used to obtain the same effect on properties. Tantalumfree alloys and/or alloys wherein not more than 50% of the columbium content is replaced by tantalum are notchductile at elevated temperatures. Boron in an amount exceeding about 0.001% and up to about 0.02%, e.g., about 0.005% to about 0.015%, contributes to the strength of the alloy over the temperature range from about atmospheric temperature to about 1400 F. Boron contributes particularly to high strength and ductility in the stress-rupture test at elevated temperatures. The alloy may also contain up to about 0.5% zirconium, e.g., about 0.05% to about 0.3% zirconium. Zirconium functions as a malleabilizer and deoxidizer and contributes to age hardening.

The alloys are soft and ductile in the annealed or solution-treated condition, i.e., after a heat treatment at a temperature of at least about l550 or 1600" F. up to about 2200 F. for a period of about 1 hour. The alloys respond readily to age hardening in the temperature range a of about 1200 to 1350 F. for periods of time of at least about 4 hours and up to 24 hours, e.g., 16 hours. The alloys may be solution treated or annealed prior to aging or may be aged directly from the as-forged or hot rolled alloys defined in Table I were subjected to tensile tests at room temperature with the results set forth in the following Table III. In addition, specimens from certain of the heat treated bars were subjected to stress-rupture tests TABLE I A110 Percent Percent Percent Percent Percent Percent Percent Percent Percent Percent No. Fe Ni Cr Al Ti 0 Si 0.05 16.97 40.73 20.20 0.46 0. 58 1. 99 3. 85 0.010 0.23 0.07 28.55 45. 96 14. 58 0.59 0.52 2. 93 6.16 0.005 0.27 0. 05 21. 75 49.27 20. 77 0.66 0.61 2.06 4. 23 0.006 0.29 0. 06 14. 5O 52. 74 20. 37 0. 60 0. 68 4. 99 5. 38 0. 005 0. 31 0.05 13. 19 52.85 20. 69 0. 68 0. 69 5. 91 5. 24 0.005 0.33 0.04 15. 04 53. 08 22.93 0. 62 0. 66 2. 34 4. 61 0.006 0.33 0.04 15.09 53 35 21.14 0.48 0. 62 4.15 4. 18 0.007 0. 18 0.03 16. 99 53. 44 21.38 0. 63 0.61 2.15 4. 27 0.009 0.27 0.04 Bal 53. 45 21.21 0.33 0. 30 2.15 4. 32 0.008 0.27 0. 05 19. 59 53. 58 18. 26 0. 60 0. 62 2. 4. 52 0.005 0. 32 0. O4 15. 44 54. 20.85 0. 66 0. 68 2. l0 5. 0.005 0. 33 0. 05 13. 74 54. 29. 47 0. 66 0. 65 5. 01 4. 45 0.005 0.34 0. 04 16. 02 54.34 20. 85 0.55 0. G2 3. 22 3. 79 0. 007 0.30 0.05 16. 50 54.35 20. 60 0.52 0. 64 2. 95 3. 81 0. 006 0.32 0.04 16. 66 54.45 20. 70 0.98 0.63 2.03 3. 94 0. 007 0.31 0. O4 16. 26 54. 89 20. 53 0. 53 1. 00 2. 02 4. 16 O. 007 0.30 0. 04 18. 36 55. 46 14. 91 0. 59 O. 59 3. 00 6. 39 0. 006 0. 29 0.04 14. 36 55. 97 20.11 0.61 0.64 2. 50 5.10 0.005 0.31 0.05 11. 93 58. 44 21.06 0.60 0.68 2.13 4. 42 0. 004 0.34

1 Alloy contains 14.67% of cobalt. 5 Boron added to melt.

Nora-The values reported for columbium in the foregoing alloys include about 10% by weight of tantalum The alloys also contained manganese in the range of 1.01% to 0.34%.

condition. It is a feature of the alloys described hereinbefore that they develop high stress-rupture properties at 1200 F. when directly aged from the hot rolled or asforged state without a solution anneal. The alloy in the as-cast condition is readily wrought using commercial hot working operations such as rolling, forging, extrusion, etc.

For the purpose of giving those skilled in the art a better understanding of the invention, the following illustrative examples are given:

A number of alloys having the compositions set forth 4, in the above Table I were melted in an induction furnace open to the air and were cast into graphite molds to form 4-inch diameter round ingots. The ingots were forged to bars approximately /a of an inch square using a series of forging and reheating steps. The ingots were forged without difliculty.

Specimens from the bars obtained in the foregoing manner were subjected to various heat treatments as set forth in the following Table II.

TABLE 11 Heat Treatment Procedure Heat Initial heating Reheating treatment As forged d 1,250 F., 16 hours. 1,300" F., 16 hours. 1.325" F., 16 hours. 1,350 E, 16 hours. 1,500 F., 1 hour; W.Q- 1,300 E, 16 hours. 1,550 F., 1 hour; W.Q 1,250 F., 16 hours. -d0 1,275 F., 16 hours. ..d 1,300 E, 16 hours.

1,600 F., 1 hour; W.Q. Do. 1,650 F., 1 hour; W. Q 1,250 F., 16 hours. .--.do 1,275 F., 16 hours.

1,300 F., 16 hours.

Do. 1,250 F., 16 hours. 1,300 E, 16 hours.

1,250 E, 16 hours. 1,300 F., 16 hours. 1,325 F., 16 hours. 1,350 F., 16 hours. 1,300 F., 16 hours. 1,350 F., 16 hours.

NorE.-W.Q.=Water quenched.

Specimens of heat treated bar stock made from the at elevated temperatures of 1200" F. or higher with the results set forth in the following Table IV.

TABLE III Room Temperature Properties Yield strength, p.s.i. Tensile Alloy H.T. strength, EL, R.A.,

No, p.s.i. percent percent 0.02% set 0.2% set B A 110,500 117,500 150,500 35.0 58. 5 B 155,500 171,500 197,000 24.0 50.5

15 R 102,500 111, 500 177,500 40. 0 51. 5 16 S 115,000 132,500 180,500 36.0 49.5 17 C 208,000 231, 500 239, 560 15.0 36. 5 P 45, 000 55, 000 126, 000 49. 0 61. 5

18 C 182,000 201,500 216, 500 15.0 46. 5 P 41, 000 52, 000 125, 000 56.0 67. O

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g about 00 F, 5 R, e.g., about 1350 R, the alloy should be solution treated or annealed prior to aging. This solution treatment involves a heating in the te about 1800 F. to about 2000 is the criterion, conmperature range of F. for a period of time tains about 4% to about 8% colurnbium, about 13% to about 23% chromium denum, about 0.2%

about 2% to about 5% molybto about 2% aluminum about 0 2% up to about 8 hours, e.g., about 1 to about 8 hours. with the sum of aluminum and 60 titanum not exceeding about 2%, not over about 0.5% silicon, up to about 1% manganese, more than 0.001% up to about 0.02% boron, em, about 0.005% to about In order to give those skilled in the art a better understanding of the properties and advantages of the foregoing high nickel alloys, the following illustrative examples are given:

to about 2% titanium W p A number of alloys having the compositions set forth in )0 0.015% boron, not more than about 0.1% carbon, up to about iron, and the balance essentially metal from the group consisting of nickel and cobalt with the balance e following table V were melted and processed in the same manner as the alloys given in Table I hereinbefore.

bar stock made from the alloys subjected to room temperature 0 tensile tests with the results set forth in the following an M6 eW U v 6 hm a 0T mm md 6 De Sd being about 60% to about 75% of the alloy with the nickel content being at least about and with the cobalt content being up to about of the alloy.

Table VI. In addition, specimens from certain of the heat treated bars made of alloys defined in Table V were subjected to stress-rupture tests at elevated temperatures In these alloys, the sum of the columbium and molybdenum contents advantageously is at least about 7%.

Aluminum and titanium in the aforementioned small amounts impart malleability, additional age hardenunder the conditions and with the results set forth in the ability, and high strength to the alloy. Cobalt in the following Table VII.

test specimens employed were machined from forgings and were subjected to a heat treatment prior to testing, which treatment comprised a heating at 1900-2000 F. for one hour, a quench in water, and a reheating at 1300-1350 F. for sixteen hours, followed by air cooling. The curves labeled A and B show, respectively, the tensile and yield (0.2% offset) strengths for the alloys at room temperature. The curves labeled C, D and E show, respectively, the 100-hour rupture strength for the alloys at 1200 F., 1300 F. and 1400 F. The data presented in the drawin demonstrate that the maximum room temperature strength is obtained in the alloys at about 53% nickel and that increasing the nickel content beyond 53% increases the rupture strength for the alloys at elevated temperatures.

It will be evident from the foregoing that the present invention is directed to age hardenable nickel alloys containing about to about 25% chromium, up to about 7% molydenum, about 3% to about 8% columbium, about 0.2% to about 2% titanium, about 0.2% to about 2% aluminum, with the sum of aluminum and titanium not exceeding about 2.5%, not more than about 0.2% carbon, up to about 0.02% boron, up to about 40% iron, and the balance essentially a metal from the group consisting of cobalt and nickel with the sum of the nickel and cobalt contents being about 45% to about 80% of the alloy and the cobalt content being up to about 40% of the alloy and the nickel content being at least 30%. In these alloys generally, it is advantageous that the sum of the columbium and molybdenum contents be at least about 9% and up to about and that the amount of columbium be at least about 4%. Aluminum and titanium in small amounts are essential to provide malleability, additional age hardenability and high strength in the alloy and must be present in amounts of at least about 0.2% each. It is important that alloys within the invention have contents of columbium plus tantalum, aluminum plus titanium, chromium and nickel as related according to the following formulae:

(1) For nickel contents of 50% and over,

(2) For nickel contents less than 50%,

The alloy may be substantially or entirely copper free or may contain up to about 4% copper, preferably not over about 0.15% copper. Cobalt in the alloy is beneficial from the standpoint of improving properties at elevated temperature and, in addition, cobalt enables the use of lower annealing or solution-treating temperatures. Molybdenum in the alloy contributes to the elevated temperature strength properties thereof but does not contribute age hardenability to the alloy. The molybdenum content of the alloy may be replaced in whole or in part by an equal weight amount of tungsten while retaining substantially the same properties although the hot malleability of the alloy is reduced thereby. Columbium in the alloy may be replaced in part with tantalum in the amount of up to about 4% of the alloy without materially changing the properties of the alloy. In partially replacing the columbium content of the alloy with tantalum, double the weight of tantalum should be used to obtain the same effect upon properties. Tantalum-free alloys and/or alloys wherein not more than 50% of the columbium content is replaced by tantalum are notchductile at elevated temperatures. Since commerciallyavailable columbium contains about 10% tantalum, the values reported herein for columbium include about 10% by weight of tantalum. Boron in an amount exceeding 0.001% and up to about 0.02%, e.g., about 0.005% to about 0.015%, contributes to the strength of the alloy over the temperature range from about atmospheric temperature to about 1400 F. Boron contributes particularly to high strength and ductility in the stress-rupture test at elevated temperatures. The alloy may also contain up to about 0.5% Zirconium, e.g., about 0.05% to about 0.3% zirconium, which functions as a malleabilizer and deoxidizer and contributes to age hardening.

When it is stated herein that the balance of the alloy is metal from the group consisting of nickel and cobalt, it is to be understood that the balance will include small amounts of impurities and incidental elements which do not materially change the properties of the alloy. Thus, impurities such as sulfur and phosphorus in a total amount up to about 0.05% may be present in the alloy. The alloy may contain up to about 1% silicon, but the silicon content should not exceed this amount as otherwise forgeability of the alloy is impaired. Advantageous- 1y, silicon does not exceed 0.5% to secure best properties at elevated temperatures. Manganese in an amount up to about 1% may be present in the alloy. The alloy is readily age hardenable when heated in the temperature range of about 1200 to about 1350 F. for periods of time of at least 4 hours and up to 24 hours, e.g., 16 hours. The alloy may be aged to develop high strength either directly from the as-forged or hot rolled condition or after a solution treatment at a temperature of about 1550 F. to about 2200 F. for a period of about 1 hour. In the aged condition, the alloys are strong and ductile and do not develop brittleness after long exposure to stress at elevated temperature.

Reference to the data in the foregoing tables demonstrates that alloys contemplated in accordance with the invention possess a very high combination of strength and ductility. Thus, these alloys generally will provide a room temperature yield strength of at least. 100,000 p.s.i. or much hi her along with a substantial elongation which usually isat least 20%. In addition, many of the alloys contemplated in accordance with the invention will provide a 10"-hour rupture strength of at least about 110,000 p.s.i., or much higher,.at 1200" F. As an example, alloy No. 25 displayed a rupture life of 482.8 hours at 1200 F. and 100,000 p.s.i. Alloys within the invention are strongly age hardenable and will provide a room temperature yield strength in the aged condition which is at least 50% or or more than the room temperature yield strength for the same alloy in the solution annealed condition.

The small content of aluminum and titanium required in the allo which advantageously is a total of at least about 0.75%, contributes very importantly to the age hardena-bility of the alloy and to the development of high strength in the alloy at elevated temperature. As an example, an alloy outside the scope of the invention and containing about 0.07% carbon, about 18.26% iron, about 53.42% nickel, about 20.95% chromium, about 0.024% aluminum, about 0.041% titanium, about 2.08% molybdenum and about 4.59% columbium was essentially non-age hardenable and developed a room temperature yield strength (0.2% set) of only 68,000 psi. and had a 100-hour rupture strength at 1200 F. of only about 75,000 p.s.i. in contrast thereto, comparable alloys Nos. 9 and 8 developed room temperature yield strengths (0.2% set) in the aged condition of 167,500 p.s.i. and 190,000 p.s.i., respectively, and were character- 0 ized by 100-hour rupture strengths at 1200 in the aged condition of 100,000 psi. and 105,000 p.s.i., respectively. On the other hand, the sum of aluminum and itanium does not exceed about 2.5% or, more advantageously, about 2%, as greater amounts of these elements reduce the rupture strength of the alloy at elevated temperatures and also greatly reduce forgeability of the alloy.

In anotl er example, a commercial-scale melt weighing about 5000 pounds was air melted in a commercial induction furnace. This melt contained about 4.29% colum- 11 bium, about 2.45% molybdenum, about 20.81% chromium, about 17.66% iron, about 53.02% nickel, about 0.009% boron, about 0.39% aluminum, about 0.64% titanium, about 0.39% silicon, about 0.05% carbon and The fatigue strength (endurance limit at 10 cycles) at room temperature of hot-rolled, heat-treated bar stock made from this metal was 80,000 p.s.i. after aging at 1300 F. for 16 hours and 97,500 p.s.i. after aging at about 0.29% manganese. Six ingots weighing about 550 1325 F. for 16 hours. In addition, it was found that pounds each and two ingots weighing about 825 pounds hot-rolled bar stock made of this metal displayed exceleach were produced. The ingot surfaces were machlned lent resistance to the destructive effects of boiling nitric to remove skin defects. The ingots were then heated to acid both in the as-rolled and the as-rolled and aged condiabout 2050 F. and were forged to billets having a sec-' 10 tions. tion of about 3 inches by about 7 inches. The billets were In another example, another commercial-scale melt heated to about 2050 F. and were hot rolled to various weighing about 5000 pounds was air melted in a commerrn-ill forms, including sheet, and in. diameter rounds. cial induction furnace and cast into ingots. This melt One half of a 550-pound ingot was heated to 2000" F. contained about 5.35% columbium, about 3.12% molyband extruded to 3 /2 in. diameter round. denum, about 15.56% chromium, about 8.85% iron, about The forging and rolling operations were conducted 65% nickel, about 0.003% boron, about 0.47% alumiwithout difiiculty. num, about 0.92% titanium, about 0.32% silicon, about Hot-rolled sheet 0.082 inch thick and cold-rolled sheet 0.30% manganese and about 0.03% carbon. The ingots 0.070 inch thick made [from the alloy were aged by heatwere overhauled to remove surface defects and were ing for 16 hours at 1300 F. In addition, cold-rolled 20 heated and forged to billets. The billets were reheated sheet 0.060 inch thick made from the alloy was annealed and hot rolled to various mill forms, including hot-rolled at 1800 F. in a production gas-fired continuous annealrounds about inch in diameter. Tensile data were obing furnace, and was then aged by heating for 16 hours tained upon the hot-rolled rounds in two conditions of at 1300 F. These sheet materials were subjected to tenheat treatment and over a range of temperatures with the sile testing over a range of temperatures with the followfollowing results: ing results:

Yield Test strength Tensile Elon- R.A., Yield Condition temp, (0.2% strength, gation, percent Test stren th Tensile Elon- F. fset), 13.5.1. percent Condition temp., (0.2% strength, gation, p.s.1

F 011001;), p.s.1'. percent .S.1 p Hot-rolled, aged 10 hrs. 85 103, 000 109,000 31.0 51.4 at1325 F, 400 152,000 185,000 20.0 50.2 0.082 inch hot-r0lled, aged 85 153,000 179,000 23.0 800 151,000 178,000 5.0 47.0 000 14 ,000 100, 220 1,000 145,000 177,000 25.0 42.0 800 139,500 155,000 1 .5 1, 200 140,000 105,000 11.0 14.0 1,000 132,000 148,000 17.5 40 1.300 137.000 00 5.0 14 4 1,200 131,000 151,000 21 1, 400 109,000 111,500 5.0 10.1 1,300 124,000 130, 500 14.0 1,500 00 6 .000 3.0 24.5 1 400 101 000 105 000 5 Hot-rolled, annealed 1 85 133,000 174, 000 38.0 44.6 1, 500 50,000 51,000 610 hr. 501,950 F., Water 400 123.000 158,500 35.0 51.4 0070111511 c0ld-ro1led,agedl' 85 158,000 125, 000 22.0 quenched and 2 d 16 800 119.500 .000 34.0 50.2 000 143,000 100, 500 2 hrs. at1,325 F. 1,000 115,500 144,000 33.0 54.0 300 143,000 159 500 145 v 1, 200 115,500 148,000 39.0 54.4 1,000 139,500 150,000 17. 1,300 112,000 133,000 10.0 21.0 1,200 137,000 153, 500 27.0 1.400 98.000 00 1 .0 17.5 1,300 130,000 137, 000 18.5 1.500 0 74,0 30.0 45.8 1,400 98,000 100,000 27.0 1,500 59,500 02,000 41.0 0.000 inch cold-rolled, annealed and aged 85 134,500 175,500 27.5

11 140,500 34.3 ,3 11 120,000 27. 1,400 93, 0 97,000 5 Additional examples of alloys wlthm the scope of the 1,500 59,500 60,000 lnvention and the properties thereof are given in the following tables:

TABLE VIII Alloy No. Percent Percent Percent Percent Percent Percent Percent Percent Percent Percent Fe N1 r i M0 Ch 1 B 2 Boron added to melt.

TABLE IX Yield strength, p.s.i. Tensile Allo H.'I. strength, El., 12.11,,

No. p.s.i. percent percent 0.02% set 0.2% set 33 C 182, 500 205, 500 239, 500 11v 30. 6 SS 153, 000 175,500 214, 000 21.0 37. 8 34 C 190, 500 248, 500 255, 500 5. 0 16.7 T 174,000 198,000 222, 500 12.0 18. 8 35 O 217, 500 248, 000 260,500 2.0 9. 3 S 179, 000 205, 500 223, 500 10.0 10.0 36 CC 263,000 270, 000 9. 0 23. 9 '1 191,000 233, 500 16.0 21. 7 37 D 199,500 214,000 12.0 45. 0 'P 49,500 122,000 53. 0 64. T 132, 500 183, 500 29.0 50. 0 11 185,500 211,500 1'7. 0 34. 0 38. C 225,000 239, 000 10.0 29. 0 T 150, 000 196, 000 26. 5 38. 0 39 C 203, 000 225, 500 8. 0 26. 0 P 52, 000 121,000 49. 0 53. 5 T 135,000 191, 000 23. 0 35. 0 40 B 142, 000 152,000 182,500 24.0 51.5 G 140, 500 163,500 101, 500 20.0 31.0 41 C 160,000 179,000 201.500 16.0 42. 5 H 100, 000 181, 500 206,000 17.0 35. 0 P 55, 500 47, 500 117,000 55.0 69.0 S 144,000 160, 000 107, 500 24. 0 39.0 42 C 161, 500 176. 000 197, 000 17.0 46. 0 11 148,000 167,000 191, 000 16. 0 45. 5 P 36,500 47, 500 118, 500 46. 0 65. 5 S 111, 000 125, 000 170,000 28. 0 48. 0

TABLE X Temper- Stress, Life, EL, RA

Alloy No. H.T ature, p.s.i. hrs. perpor- F, cent cent V 1, 300 80,000 37. 6 4.0 10.0 V 1, 300 80,000 87. 3 11.0 28. 5 V 1, 300 80,000 62. 8 19. 5 33. 5 V 1,300 80, 000 35. 6 3.0 4. 5 C 1,200 100, 000 114.1 4v 0 17.5 0 1,200 100, 000 115. 4 S. 5 11.5 0 1, 300 60.000 145. 3 19. 5 43.0 0 1,350 45, 000 189. 3 7. 0 12. 5 S 1,200 100.000 73. 5 4. 0 10.0 38 0 1,200 100,000 130.4 7.0 21.5 0 1, 200 100, 000 51. 4 10.0 14. 5 O 1, 300 65, 000 98.1 18. 0 25.0 0 1, 350 50, 000 71. O 22.5 32.0 0 1,500 20, 000 55.0 33. 5 62.0 39 0 1,200 100,000 33. 7 17.0 31.0 0 1, 200 100,000 48. 7 4.0 6. 5 0 1,300 ,000 67. 4 14. 0 16.5 0 1, 350 50, 000 68. 0 17. 0 19.0 0 1,500 20,000 69.9 33. 5 40. 5 40 B 1, 200 90,000 252. 3 9.0 28.0

Alloys contemplated in accordance with the invention may be produced by melting the required ingredients together in a furnace satisfactory for melting high-nickel alloys. Additions of aluminum, titanium, columbium and boron are made late in the melting cycle. Additional deoxidation with magnesium or calcium may be employed.

The alloys produced in accordance with the invention are characterized by the fact that they provide high strength properties as reflected in the stress-rupture test at elevated temperatures of about 1200 F. to 1400 F. in the as-rolled and aged condition. The alloys within the invention are characterized by an essentially featureless microstructure even after prolonged exposure to the deleterious eifects of combined stress and temperature. The alloys within the invention are characterized by high fatigue strength over a range of temperatures up to about 1400 F. The microstructure displays clean grain boundaries and shows no precipitate other than carbides at usual optical magnifications in the aged condition.

The alloy can be produced in the usual hot-worked mill forms, including sheet, strip, rods, bars, tubing, etc. The alloy is useful in a wide variety of applications as a structural member in air frames, missiles, rockets and the like. It is also useful for compressor and turbine rotors in gas turbines. It is also useful as compressor and turbine blading in gas turbines and as turbine blading in steam turbines. The alloy may also be used in a variety of forms such as sheet and tubing in applications such as pressure vessels, steam lines, high-temperature piping and the like. The alloy may also be used in hightemperature bolts such as those used in aircraft gas turbines, stationary gas turbines and steam turbines and it is also useful in the form of springs subjected in use to elevated temperatures. The corrosion resistance of the alloy is good.

In addition, the alloy provides a very high ratio of strength to density (the Shapiro index). The alloy is non-magnetic.

it is to be noted that all alloy compositions given herein are expressed in percentage by weight.

Although the mechanism involved in producing the greatly enhanced properties provided by alloys contemplated in accordance with the present invention is not fully understood, it is believed that the columbium content of the alloys is basically responsible for the exceptional properties developed in the age-hardened alloys. These exceptional properties include a unique and heretofore undisclosed combination of high room temperature and elevated temperature strength properties along with high ductility.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

I claim:

1. An age-hardenable, hot-workable nickel-base alloy consisting essentially of about 21% chromium, about 3% molybdenum, about 4% of metal from the group consisting of columhium and tantalum wherein the tantalum content does not exceed about 50% of the colu-mbium, about 0.6% titanium, about 0.6% aluminum, about 0.03% carbon, about 0.27% silicon, about 0.18% manganese, about 0.009% boron, about 53% nickel, and the balance essentially iron, said alloy being characterized in the age-hardened condition by a yield strength (0.2% oifset) of at least about 100,000 pounds per square inch at room temperature and by a -hour rupture strength of at least about 90,000 psi. at 1200 F.

2. An age-hardenable, hot-workable nickel alloy c0nsisting essentially of about 15% to about 231% chromium, about 2% to about 4% molybdenum, about 4% to about 8% of metal from the group consisting of colum bium and tantalum wherein the tantalum content does not exceed about 50% of the columbium, aluminum and titanium each in a small amount of at least about 0.2%, with the total aluminum plus titanium content not exceeding about 2%, not more than about 0.1% carbon, not more than about 0.5% silicon, about 0.005% to about 0.015% boron, up to about 30% iron, up to about 1% manganese, and the balance essentially metal from the group consisting of nickel and cobalt, with the sum of the nickel and cobalt contents being about 45% to about 60% of the alloy, with the nickel content being at least about 30% of the alloy, said alloy being characterized in the age-hardened condition by a yield strength (0.2% offset) of at least about 100,000 pounds per square inch at room temperature and by a 100-h0ur rupture strength of at least about 90,000 p.s.i. at 1200 F.

3. An age-hardenable, hot-workable nickel alloy consisting essentially of about 15% to about 23% chromium, about 2% to about 4% molybdenum, about 4% to about 8% of metal from the group consisting of columbium and tantalum wherein the tantalum content does not exceed about 50% of the eolumbiurn, aluminum and titanium each in a small amount of at least about 0.2%, with the total aluminum plus titanium content not exceeding about 2%, not more than about 0.1% carbon, not more than about 0.5% silicon, about 0.001% to about 0.02% boron, up to about 30% iron, up to about 1% manganese, and the balance essentially nickel,

with the nickel content being about 45 to about 60% of the alloy, said alloy being characterized in the agehardened condition by a yield strength (0.2% offset) of at least about 100,000 pounds per square inch at room temperature and by a l-hour rupture strength of at least about 90,000 p.s.i. at 1200 F.

4. An age-hardenable, hot-workable nickel alloy consisting essentially of about 15% to about 23% chromium, about 2% to about 4% molybdenum, about 4% to about 8% of metal from the group consisting of columbium and tantalum wherein the tantalum content does not exceed :about 50% of the columbium, aluminum plus titanium each in a small amount of at least about 0.2%, with the total aluminum plus titanium content not exceeding about 2%, not more than about 0.1% carbon, not more than about 0.5% silicon, about 0.005 to about 0.015% boron, up to about 30% iron, up to about 1% manganese, and the balance essentially metal from the group consisting of nickel and cobalt, with the sum of the nickel and cobalt contents being about 51% to about 56% of the alloy and the nickel content being at least about 30% of the alloy, said alloy beingcharacterized in the agehardened condition by a yield strength (0.2% offset) of at least about 100,000 pounds per square inch at room temperature'and by high rupture strength at temperatures up to about 1400 F.

5. An age-hardenable, hot-workable nickel-base alloy consisting essentially of about 13% to about 23% chromium, about 2% to about 5% molybdenum, about 4% to about 8% of metal from the group consisting of columbium and tantalum wherein the tantalum content does not exceed about 50% of the columbium, aluminum and titanium each in a small amount of at least about 0.2%, with the total aluminum plus titanium content not exceeding about 2%, not more than about 0.1% carbon, not more than about 0.5% silicon, about 0.001% to about 0.02% boron, up to about 20% iron, up to about 1% manganese, and the balance essentially metal from the group consisting of nickel and cobalt, with the sum of the nickel and cobalt contents being about 60% to about 75% of the alloy, with the nickel content being at least about 30% of the alloy, and with the cobalt content being up to about 40% of the alloy, said alloy being characterized in the age-hardened condition by a yield strength (0.2% offset) of at least about 100,000 pounds per square inch at room temperature and by a 100-hour rupture strength of at least about 100,000 p.s.i. at 1200 F.

-6. An age-hardenable, hot-workable nickel alloy consisting essentially of about chromium, about 3% molybdenum, about 7.5% of metal from the group consisting of columbium and tantalum wherein the tantalum content does not exceed about 50% of the colum-bium, about 0.7% titanium, about 0.7% aluminum, about 0.04% carbon, about 0.3% silicon, about 0.005% boron, about 8% iron, about 0.3% manganese, and the balance essentially nickel, said alloy being characterized in the agehardened condition by a yield strength (0.2% offset) of at least about 100,000 pounds per square inch at room temperature and by a 100-hour rupture strength at 1200 F. of at least about 100,000 pounds per square inch.

7. An age-'hardenable, hot-workable nickel alloy consisting essentially of about 10% to about 25% chromium, about 2% to about 7% of metal from the group consisting of molybdenum and tungsten, more than 3% and up to about 9% of metal from the group consisting of columbium and tantalum with the tantalum content not exceeding about 50% of the columbium, aluminum and titanium each in a small amount of at least about 0.2%, with the total aluminum plus titanium content not exceeding about 2.5%, not more than 0.2% carbon, not more than 0.5 silicon, about 0.001% to about 0.02% boron, up to about 30% iron, up to about 1% manganese, and the balance essentially metal from the group consisting of nickel and cobalt, with the sum of the nickel and cobalt contents being about 45% to about of the alloy, with the nickel content being at least about 30% and with the cobalt content being up to about 40% of the alloy, said alloy being characterized in that when the nickel content is at least 50%, the contents of columbium plus tantalum, aluminum plus titanium, chr0- mium and nickel are related such that is at least equal to 8.5; and when the nickel content does not exceed 50%, the contents of these elements are related such that is at least equal to 8.5, and being further characterized after hot working and aging by a yield strength (0.2% ofiset) of at least about 100,000 pounds per square inch at room temperature and by a -hour rupture strength of at least about 90,000 p.s.i, at 1200 F.

8. An age-hardenable, hot-workable nickel alloy consisting essentially of about 10% to about 25% chromium, about 2% to about 7% of metal from the group consisting of molybdenum and tungsten, more than 3% and up to about 9% of metal from the group consisting of columbi-um and tantalum wherein the tantalum content does not exceed 50% of the columbium, aluminum plus titanium each in a small amount of at least about 0.2%, with the total aluminum plus titanium content not exceeding about 2.5%, not more than 0.2% carbon, not more than 1% silicon, about 0.001% to about 0.02% boron, up to about 0.5% zirconium, up to about 1% manganese, up to about 30% iron and the balance essentially nickel, said alloy being characterized after hot working and aging by a yield strength (0.2% offset) of at least about 100,000 pounds per square inch at room temperature and by a 100-hour rupture strength of at least about 90,000 p.s.i. at 1200 F.

9. An age-hardenable, bot-workable nickel alloy consisting essentially of about 10% to about 25% chromium, about 2% to about 7% molybdenum, about 4% to about 9% of metal from the group consisting of columbium and tantalum wherein the tantalum content does not exceed about 50% of the columbium, about 0.75% to about 2% of metal from the group consisting of aluminum and titanium, not more than about 0.1% carbon, not more than about 0.5 silicon, about 0.001% to about 0. 02% boron, up to about 30% iron, up to about 1% manganese, and the balance essentially nickel, said alloy being characterized after hot working and aging by a yield strength (0.2% offset) of at least about 100,000 pounds per square inch at room temperature and by a rupture strength of at least about 90,000 pounds per square inch at 1200 F.

References Cited in the file of this patent UNITED STATES PATENTS 1,675,798 Frank et a1. July 3, 1928 2,432,618 Franks et al Dec. 16, 1947 2,570,193 Bie'ber et a1. Oct. 9, 1951 2,575,915 Guy Nov. 20, 1951 2,712,498 Gresham et al. July 5, 1955 2,766,155 Betteridge et a1. Oct. 9, 1956 2,860,968 Boegehold et a1 Nov. 18, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,046,108 July 24, 1962 Herbert L. Eiselstein It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Columns 3 and 4, TABLE I, first column thereof, strike out the superscript "2" after "11" and insert the same after "12"; same TABLE I, fourth column thereof, in the nickel percentage "53 35" for Alloy No. 7, read 53.35 same table, fifth column thereof, for the chromium percentage "29.47" for Alloy No. 12, read 20.47 same TABLE I, eighth column thereof, the symbol "W" for tungsten should be inserted after "4.15", for Alloy No. 7; same columns 3 and 4, in the explanatory note directly below TABLE I, for "1.01%" read 0.01% column 5, TABLE IV, fifth column thereof, figure for heat treatment "S" of Alloy No. 12, for "127,1" read 127.1 columns 7 and 8, TABLE V, seventh column thereof, for the titanium percentage "5.53" for Alloy No. 32, read 0.53 same TABLE V, eleventh column thereof, the silicon percentages for Alloys No. 31 and 32, for "0.22" and "0.21", respectively, should be reversed to read 0.21 and 0.22 respectively; column 7, TABLE VI, fourth column thereof, the "0.2% set" Yield strength figure for "Alloy No. 31" in condition "T", for "12,500" read 121,500

Signed and sealed this 20th day of November 1962.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. AN AGE-HARDENABLE, HOT-WORKABLE NICKEL-BASE ALLOY CONSISTING ESSENTIALLY OF ABOUT 21% CHRONIUM, ABOUT 3% MOLYBDENUM, ABOUT 4% OF METAL FROM THE GROUP CONSISTING OF COLUMBIUM AND TANTALUM WHEREIN THE TANTALUM CONTENT DOES NOT EXCEED ABOUT 50% OF THE COLUMBIUM, ABOUT 0.6% TITANIUM, ABOUT 0.6% ALUMINUM, ABOUT 0.03% CARBON, ABOUT 0.27% SILICON, ABOUT 0.18% MANGANESE, ABOUT 0.0009% BORON, ABOUT 53% NICKEL, AND THE BALANCE ESSENTIALLY IRON, SAID ALLOY BEING CHARACTERIZED IN THE AGE-HARDENED CONDITION BY A YIELD STRENGTH (0.2% OFFSET) OF AT LEAST ABOUT 100,000 POUNDS PER SQUARE INCH AT ROOM TEMPERATURE AND BY A 100-HOUR RUPTURE STRENGTH OF AT LEAST ABOUT 90,000 P.S.I. AT 1200* F. 